Air quality Environment Act target delivery plan
Statutory Environment Act targets
- annual Mean Concentration Target for PM2.5 – a maximum of 10 micrograms per cubic metre (µg m-3) to be achieved by 31 December 2040
- population Exposure Reduction Target for PM2.5 – a minimum of 35% reduction compared to 2018 by 31 December 2040
Interim targets
- an annual mean concentration target of 10 micrograms per cubic metre (µg m-3) to be achieved by December 2030
- a population exposure reduction target of 30% compared to 2018 to be achieved by December 2030
Rationale for the interim targets: why and how they will progress delivery of the Environment Act target
We increased the ambition of the interim targets in EIP25 to align more closely with the measured trajectory towards the statutory targets. The graphs below show the measured progress. Versions of these graphs will be updated each year and made available in the Air Quality publication.
Figure 1. Progress towards the Annual Mean Concentration Target (AMCT) for PM2.5 at monitoring sites, 2009 to 2025.
The data and an interactive version of this chart are available on the UKAIR interactive graphs page. Orange circles are measurements above the interim target/long-term target; and green circles meet the statutory target.
The graph in Figure 1 shows the progress towards the Annual Mean Concentration Target (AMCT). PM2.5 concentrations measured at individual monitoring sites in England from 2009 to 2025 are shown. The larger the circle, the greater the number of sites measuring this value. The 2030 interim target is the same concentration as the statutory 2040 target. To meet the target, all monitoring sites need to be at or below 10 µg m-3.
Figure 1 shows that concentrations of PM2.5 have decreased over time. The spread of measurements has also decreased as the maximum concentration has reduced more than the average. In 2025 three monitoring sites did not meet the interim 2030 target/ statutory 2040 AMCT. Most measurements in 2025 are in the range of 7 to 9 µg m-3, compared to 9 to 12 µg m-3 in 2018.The maximum concentration measured in 2025 was 12 µg m-3. This meets the EIP23 interim target for 2028 (12 µg m-3) but does not yet meet the EIP25 interim target for 2030 (10 µg m-3).
Figure 2. Progress towards the Population Exposure Reduction Target (PERT) for PM2.5: Percentage change in population exposure since 2018, 2018–2025.
The graph in Figure 2 shows progress towards the Population Exposure Reduction Target (PERT). The green columns are the accumulative change in population exposure compared to 2018 for each year. The dashed lines show the reduction in population exposure needed to meet the 2030 interim target, and the 2040 target.
Figure 2 shows that, since 2018, population exposure has decreased each year. Between 2018 and 2025 the reduction in population exposure was 26%. This exceeds the EIP23 interim target for 2028 (22%) but does not yet meet the EIP25 interim target for 2030 (30%).
The PERT metric is a 3 year average, so there is less annual variability for the PERT than for the AMCT (Figure 1). The graph shows a steady decrease in the metric whereas the maximum annual concentration may increase or decrease compared to the previous year as a result of weather conditions, although the long-term trend is similar.
Concentrations of PM2.5 decreased significantly in 2019 to 2020. Analysis commissioned by Defra suggests this reduction is likely to be due to a combination of factors such as reductions in emissions of PM2.5 precursors (pollutants which react in the atmosphere to produce PM2.5) in the UK and also in Europe (leading to a lower amount of pollution being blown in from outside the UK).
Delivery measures
The 2030 interim targets may be achieved by measures already in train (such as tighter vehicle emissions standards, which reduce emissions over time as people purchase new vehicles), but achievement is made more likely by taking additional measures. The additional measures that we will take to tackle key sources and help provide further assurance of target delivery are outlined in the EIP air quality goal. These measures are designed to reduce emissions from the major sources of PM2.5 – domestic combustion, transport and industry. Reductions in precursor pollutants (such as NOx and NH3) are also helping to deliver the PM2.5 targets.
Alongside the delivery measures outlined in this section, we also expect that net zero measures will contribute towards delivery of the interim targets.
Table 1. Summary of delivery measures under the air quality delivery plan.
| Delivery measure | Description | Estimated contribution to the interim targets | Evidence of impact | Responsible | Status |
|---|---|---|---|---|---|
| Domestic Combustion consultation | Between 22 January 2026 and 19 March 2026 Defra consulted on new measures that cut emissions from domestic combustion, whilst minimising the impact on those that need to burn and respecting traditional celebratory festivals such as 5 November and Diwali. We will publish a response to the consultation in due course. | The contribution of this measure will depend on the final policy adopted. | Domestic combustion is a major source of PM2.5 emissions contributing 20% of total UK PM2.5 emissions in 2024.[footnote 1] The consultation focused on evidence-based proposals and policy mechanisms, which, if implemented, are expected to reduce PM2.5 emissions. | Defra | In development |
| Industrial emissions consultations | We have consulted on wide-ranging reforms to industrial permitting that will reduce emissions of key pollutants including sectoral reforms for combustion, batteries and anaerobic digestion, and wider reforms to the overall framework. A response to the consultation was published on 15 April 2026. The response sets out the subsequent consultations for priority policies. We will also explore options to reduce emissions from small industrial combustion plants. | The contribution of this measure will depend on the final policy adopted. | Industrial combustion and industrial processes and product use are a major source of PM2.5 emissions, contributing 10% and 15% of total UK PM2.5 in 2024 respectively [footnote 1]. Reforms are expected to reduce emissions of PM2.5 and its precursors across multiple sectors. | Defra | In development |
| Reduced transport emissions | We are undertaking a range of actions designed to reduce emissions from transport. This includes supporting the transition to zero emission vehicles; funding research and development to accelerate the technologies necessary to decarbonise the domestic maritime sector and addressing the air quality impacts of shipping through UK Shipping Office for Reducing Emissions (UK SHORE). | Further details of the travel related measures are available under the Air goal in the EIP. It has not been possible to estimate the contribution of these measures at this point. |
Transport is the single largest emissions source for NOx (a PM2.5 precursor) and second largest for primary emissions of PM2.5. In 2024, transport accounted for 44% of all domestic NOx emissions in the UK, and 26% for domestic primary PM2.5 [footnote 1]. Ongoing actions are expected to reduce emissions across road and maritime transport over time. | Department for Transport | Various - in delivery and development |
Key milestones
Key milestones for 2026 include:
- explore options to reduce emissions from small industrial combustion plants
- government response to consultation to reduce emissions from domestic combustion
Illustrative trajectory
Since the previous version of the delivery plan, we have worked with experts to better understand the differences between measured and modelled data, including the spatial representation. As a result, we have revised how we use modelled data to create target trajectories. Figure 3 and 4 show modelled trajectories applying the new approach which more closely mimics how measurements are used for the target metrics. Although some differences between modelling and measurements remain, we believe this is a better representation of expected progress. This is an ongoing area of work as we continue to improve how we develop and use modelling to inform our understanding of target progress.
The modelling which underpins our trajectories is carried out by Imperial College London, who along with UKCEH also advise on the interpretation of the data. Reports on the development of the targets provide detailed information on the modelling methodology [footnote 2].
The business as usual (BAU) trajectory is mainly based on National Atmospheric Emission Inventory emissions projections published in 2025, and the planned trajectory is based on planned government air quality and net zero policy. Air quality modelling provides information on the concentrations of PM2.5 expected under different scenarios, taking into account direct emissions from sources such as road transport and secondary PM2.5 formed in the atmosphere from other pollutants such as nitrogen oxides and ammonia. The impact of natural sources of PM2.5 and pollution originating from outside the UK are combined with the impact of UK manmade emissions to provide an overall picture of total PM2.5 concentrations. The results of the Imperial College policy modelling are complimented by modelling by UKCEH which uses a more sophisticated model which enables the influence of meteorological conditions and changes in atmospheric chemistry to be explored.
Figure 3. Modelled trajectories towards the Annual Mean Concentration Target (AMCT) for PM2.5 from 2018 to 2040 (these are an indicative estimate of potential future progress).
The graph in Figure 3 shows modelled PM2.5 concentrations under BAU and with planned policy up to 2040 alongside measured values from 2009 to 2025. The shading provides the 95th percentile range. The blue circles are the concentrations modelled at monitoring sites under the modelled BAU scenario, the orange circles are concentrations at monitoring stations under the planned trajectory which includes additional policies, and the green circles are verified measured progress. The size of the circles represents the number of monitoring sites measuring the stated value. The grey dashed line indicates the 2030 interim target/ 2040 long-term target. All monitoring sites need to measure an annual mean concentration of 10 µg m-3 or below in the relevant calendar year for the target to be met (for the interim target this is 2029 as the target deadline is part way through the following year).
All trajectories show a decrease in the maximum concentration over time. Concentrations under the planned trajectory are lower than the BAU trajectory, although the impact on the maximum concentration level is small.
The modelled trajectories illustrate the expected trends in average concentrations in the approximate location of monitoring stations under average weather conditions. While the modelled data is below the target the modelled trajectories do not take into account annual variations, for example due to weather, which can result in a 1 to 2 µg m-3 difference, or spatial variation within the 1km modelling grid squares. Therefore, modelled data might not fully represent the highest values expected. This effect can be seen for past years in Figure 3, where the range of measured values is typically greater than the range of modelled values, and typically the maximum measured value is greater than the maximum modelled value. This is important when considering the achievability of the AMCT as measurements at all monitoring sites need to be at or below the target level in the assessment year regardless of weather conditions or localised high concentrations for the target to be met.
The modelled trajectories should therefore not be considered in isolation, instead an expert-led assessment was carried out. The trajectories were considered alongside the known model limitations and recent measurement trends. This assessment used qualitative probabilistic language similar to that used by the IPCC[footnote 3] in climate change assessment to assess how likely target achievement is based on all the evidence (see Table 1).
Table 1: Terminology for evaluation of likelihood
| Term | Likelihood of the outcome |
|---|---|
| Virtually certain | 99% to 100% |
| Very likely | 90% to 100% |
| Likely | 66% to 100% |
| More likely than not | 50% to 100% |
| About as likely as not | 33% to 66% |
| Unlikely | 0% to 33% |
| Very unlikely | 0% to 10% |
| Exceptionally unlikely | 0% to 1% |
Measurements have shown greater reductions in recent years than indicated by modelling, however given the known bias to underestimate high concentrations in the modelling, experts assessed that it is about as likely as not (such as, possible) that the 2030 interim target would be met under the BAU or planned trajectory. It is more likely that the target would be met in 2040, and the planned actions make achieving both the interim and long-term targets more likely. This is a more cautious conclusion on target achievement than would be inferred from the modelled trajectories alone.
Figure 4. Modelled trajectories towards the Population Exposure Reduction Target (PERT) for PM2.5, 2018 to 2040 (these are an indicative estimate of potential future progress).
The graph in Figure 4 shows the modelled PERT trajectories from 2018 to 2040. The blue line is the modelled BAU trajectory, the orange line is the planned trajectory, and the green line is verified measured progress up to 2025. The light blue dashed line is the 2030 interim target and the darker blue dashed line is the 2040 long-term target.
Both modelled trajectories and measured data decrease over time, with the planned trajectory decreasing more than the BAU trajectory. Recent measured data has shown greater reduction than the modelled data. Defra commissioned analysis suggests this is due to reductions in UK and European emissions of precursor pollutants.
As the PERT is based on the change in the average exposure across the country and is averaged over three years, modelling represents this metric better than the AMCT. However, it does not fully represent the recent concentration reductions measured. Therefore, as with the AMCT, the modelled trajectories were considered within the context of the modelling limitations and trends in measured data. The same language set out in Table 1 was used to assess the achievability of the interim and long-term PERT.
Using both modelled and measured evidence experts assessed that under the BAU scenario it is as likely as not (such as, possible) the interim target will be met, but that it is likely to be met under the planned trajectory. It was assessed that under the BAU scenario it is as likely as not (such as, possible) that the long-term target is met, but that it is likely to be met under the planned scenario.
All air quality modelling has multiple sources of uncertainty, including those inherent in the model (how it represents complex chemistry and dispersion processes), the input data (for example, projected UK emissions and transboundary and natural contributions), and the impact of external events such as pandemic and economic conditions. While there is a moderate degree of confidence in the assessment of the trends, assuming scenario assumptions are accurate, assumptions about the future are highly uncertain and that uncertainty increases over time. There is greater confidence in modelling the PERT than the AMCT as national scale modelling underestimates localised high concentrations and cannot capture the immediate surroundings of measurement sites, for example a nearby building site.
In addition, as weather impacts air pollutant dispersion and atmospheric chemistry, climate change may influence future air quality. When developing the long-term statutory targets, at Defra’s request, the Air Quality Expert Group held a call for evidence which covered climate change impacts.
The group’s conclusion was that it is not certain which factors will dominate so it is not possible to know the overall impact of climate change and therefore it was not practical to take this into account in Defra’s modelling.
Climate change is also likely to have a mixed effect on achieving the targets, with complex interdependencies and dependence on people’s behaviour in response to climate change. For example, milder winters may reduce the amount of domestic burning, whereas hotter summers may increase the need for air conditioning.
It is, therefore, not possible to estimate the overall impact of climate change, but it adds additional uncertainty to the level of impact measures may have on target delivery and the ease of their implementation.
Monitoring and evaluation summary
The EIP25 interim targets use the same metrics as the statutory targets and are assessed in the same way through measurements of PM2.5 concentration made at fixed monitoring locations around the country. This allows for direct assessment of progress towards the statutory targets.
Fixed monitoring for PM2.5 has been routinely carried out in the UK since 2009. The number of monitors deployed in England is set out in regulation and is determined by a minimum requirement per population head in each zone and agglomeration and there is an ongoing monitoring expansion programme underway to meet the regulatory requirements by the deadline of 31 December 2027.
For the AMCT, the highest measured annual mean concentration of PM2.5 (measured in µg m-3 and rounded to the nearest integer) at each relevant monitoring site needs to be at or below the target concentration for it to be met.
The PERT is expressed as percentage reduction compared to a base year. Population exposure is represented by a population exposure indicator (PEI) calculated using measurements from a sub-set of monitoring sites representative of population exposure. The average of the annual mean concentrations at these sites is taken to provide one value for England, which is then averaged with the 2 proceeding years to create the PEI.
A 3-year average is less affected by annual variations (for example, as a result of meteorological conditions), enabling the long-term trend to be seen more clearly. A statistical approach is used to accommodate the phased introduction of new monitors into the PERT calculation in a mathematically robust way.
Reductions in PEI between 2 consecutive years are calculated using only the monitors in operation in both assessment periods (4 years in total). Each annual incremental change in PEI is summed, to equate to the total change over multiple years and then related back to the base year of 2018 to produce the percentage change.
Monitoring site measurements need to meet data capture requirements to be included in the calculations of both targets and monitoring data is subject to a data ratification process carried out by an expert contractor. Measurement data is publicly available (as unratified data) in near real time, but the ratified annual mean (and so the verified target progress) is not available until 6 months after the end of the year.
The full calculation method for both target metrics is in the annual Air Quality publication.